I'm a 2L, and I can sympathize with constantly feeling like you're failing--that's a very common sentiment among law students, especially in your first year. Here are a few things you should keep in mind:

1) Objectively, you're actually not doing poorly in law school--you're in the top half of your class! Don't discount your own achievements. You say that the A you got last semester doesn't count because it was a bullshit class, but regardless, it was curved, which means you did very well compared to your classmates. Plus, you got the highest score on one of your midterms--that's an awesome achievement!

2) I think it's essential for you to find some measure of your self-worth that's not tied to your grades. It feels good to do well because that validates all the hard work you did, but just because you don't do well doesn't mean you didn't work hard or you're not smart. Although your grades do determine job opportunities coming out of law school (though public interest is less grade-selective than the private sector), they don't reflect your intelligence. I got much better grades the first semester of 2L compared to 1L year simply because I got more used to the exam format and developed test-taking strategies that worked for me, not because I became smarter or even because I worked harder.

3) The practice of law is so different from law school. I really enjoyed my 1L summer job, even though I was miserable in 1L year, because I got to work on things that actually had a real world impact, my work was appreciated, and I wasn't forced to compete against my peers on a curve. Stick it out through the summer, and hopefully you'll feel the same way. If you hate your summer job, then perhaps at that point you can reconsider whether law school is a good fit for you.

4) The above advice is based on the assumption that either you're going into public interest and will be on PILF or have a generous scholarship. If you're paying a lot to go to law school and want to go into the private sector, then at this point your job opportunities might be too limited for law school to be worth the cost.